In order that a video apparatus compatibly use video signals of different signalling systems, an analog signal is converted to a digital signal, and a timing signal corresponding to each portion of the video signal is generated through digital signal processing. The video apparatus receives the timing signal and generates the video signal suitable for a computer monitor for example. However, in a vertical synchronizing region of the video signal, since there is no chrominance signal, a timing signal indicating a position of a color burst signal for generating the chrominance signal should be not applied.
In the prior art, a position of a vertical synchronizing signal is sensed by counting the number of a horizontal synchronizing signals of a specific broadcasting system. Therefore, the compatibility with the video signals of difference broadcasting systems such as NTSC, PAL, etc. is difficult.